This invention relates to a rotatable anvil for cutting apparatus, and more particularly to such an anvil which is held in a support by a magnet and includes a rotator which produces random angular incremental rotation of the anvil intermediate cutting strokes of the knife.
In various cutting apparatus, such as veneer clippers which are used to cut veneer into desired lengths, it is common to use an elongate shape-edge knife which is reciprocated toward and away from an anvil. To aid in preservation of the sharp edge on the knife resilient materials may be used on the anvil to produce a striking surface for the edge of the knife.
Previously developed anvils have included those which include an elongate core which is substantially completely covered on its circumferential surfaces by a resilient material. In an attempt to obtain a degree of rigidity in the anvil previous anvils have been in a range from 5 and 6 inches in diameter.
Such previous anvils, although they provide several inches of usable striking surface, present several problems. First is the weight of such an anvil. In the most frequently used clipper size having a 120 inches long anvil for cutting 8 foot veneer, the core would weigh approximately 600 lbs. This presents a problem for maintenance crews since it cannot be easily handled by two men without the aid of hoisting apparatus.
A second problem with such previously developed anvils is that to accommodate full use of the resilient anvil surface, it must be rotated periodically between knife strokes so that a relatively new knife contact is available. Previously developed anvils generally have been supported at their opposite sets of ends by large bearings, or journals, and only intermittently between the bearings by narrow saddle sections. Since the surface of such an anvil becomes roughened due to the cutting of a knife in its striking of the anvil, substantial friction occurs between the anvil and its supportive saddles whereby excessive energy requirements are imposed on the rotator mechanism to produce rotation of the anvil during operation.
Another problem with previous anvils is their stability and firmness. Since previous anvils of this nature have had their total circumference covered with a resilient material this material provides support for the anvil where it rests in the spaced saddle sections. The resilient material will compress when the anvil is struck by the knife and will rebound when the knife retracts, thus causing the entire anvil to rebound toward the knife. This, plus the fact that the support saddles have provided only intermittent support, has produced a certain amount of anvil surface flutter. This, plus the fact that certain combinations of knife strokes may tend to set up harmonic vibrations in the anvil, often produces a variable, rather than a stable anvil surface for the knife to strike against and will produce a less than desirable cutting effect.
A general object of the present invention is to provide a simple and economically constructed anvil which overcomes the disadvantages and problems of previously developed devices as set out above.
More specifically, an object of the invention is to provide cutting apparatus including an anvil, wherein the anvil includes a magnetically attractable element having an arcuate lower surface and a resilient arcuate upper striking surface, and support means for the anvil including a cradle in which the lower surface of the element rests with a magnet therein magnetically attracting the element to hold it in the cradle. With such construction, a relatively lightweight anvil element may be used and the magnet will hold the anvil firmly in the cradle while still permitting rotation of the anvil to present different portions of the striking surface to the knife.
Yet another object is to provide novel cutting apparatus in which the anvil includes an elongate, rigid member resting in direct contact with the supportive surface of the cradle and having a covering of resilient material secured to an upper portion only thereof. With such construction, a resilient striking surface is provided for the knife, while the underside of the element may be firmly supported by the cradle to prevent the previously described undesirable characteristics of previous devices affecting stability and firmness of the anvil during operation.
A still further object of the invention is to provide such cutting apparatus which includes novel rotator means operable to produce random angular incremental rotation of the anvil between cutting strokes of the knife. This provides more even wear of the resilient surface of the anvil producing longer life.
Another object of the invention is to provide a novel, rotatable anvil which is relatively lightweight, yet which is firmly held in direct contact with a supportive cradle throughout a major portion of the length of the anvil to eliminate the problems of rebound and harmonic vibration experienced by previously developed anvils with resilient surfaces.
A still further object is to provide cutting apparatus which includes novel means for adjusting the position of the anvil relative to the knife, whereby the position of the anvil may be finely adjusted and held in selected position relative to the knife.